In the production of equipment, components of the equipment are tested to determine that the component is working properly. One such test is to determine if a drive mechanism is rotating the component properly based on the input when the drive mechanism has a load that simulates real life conditions. For example, a drive mechanism rotates a shaft to control or manipulate an air-loaded control surface, such as an air foil or rudder.
One such technique of testing is to secure a torsion bar to the end of the drive mechanism. The torsion bar is held to simulate loading of the surface.
Traditionally, the torsion bar has been clamped either with a disc brake design or high-pressure hydraulic collets. Both of these techniques have shortcomings.
The disc brake design requires pads that attach to the torsion bar. The pads are clamped with a brake caliper similar to wheels on a vehicle. However in that the pads are extruded radially from the torsion bar, the pads add rotational inertia resulting in not accurately simulating the loading of the surface. This increased rotational inertia is not desired during performance testing. In addition, the brake calipers are typically driven electrically and therefore have additional electrical requirements.
The high-pressure hydraulic collets use hydraulics to compress a collet onto the torsion bar. Either a hand pump or high-powered electric pump is typically used to provide the pressure for the hydraulics. The hand pump has many shortcomings including the additional time required by a test technician to create the needed pressure. In addition, the requirement to test components quickly, i.e., a high volume production, necessitates the need for quick connections. These quick connects and fluid leakage from collets adds a concern. The leakage could create spills that are potential safety hazards. In addition, leakage on the torsion bar clamping area would create a decrease in clamping friction requiring more clamping load. Likewise, the need for electricity for the pump makes it more difficult to test components quickly and efficiently.